Ribosomes are the complex assemblages of proteins and RNA chains which are responsible for the synthesis of proteins. Low-resolution structural maps, which have been generated by merging the data from many separate structural studies, have not been sufficient to elucidate many of the ribosome's most important structure/function relations. Only atomic-resolution structure of the ribosome can answer these questions. We plan to grow crystals of ribosomal subunits from cultured human (HeLa) cells. Subunits have been purified, and crystallization conditions will soon be tested.